I'm the original author of the QuickTrade addon that was eventually taken over by DaneBlood after I stopped playing and posting. Thank you DaneBlood!
I came back to FFXI a little over a year ago and started working on an updated, complete rewrite, but ended up leaving FFXI again before it was 100% ready for release. I stumbled across my old code today and thought I would upload it for anyone to use or takeover if they wish.
GitHub Link
I remember using it regularly and it worked well. I don't remember any bugs or problems with it, but I was one of the only people using it, so bugs were hard to spot if they existed.
I believe the core logic was complete, it was only a matter of adding and testing all of the various trades. It is MUCH easier to add trades in this version, and there are plenty of examples at the bottom of the file. If you look at the trades I already have in place, you should be able to easily figure out how to add your own. No more item IDs, and you can use the full or abbreviated names of items. I'd recommend adding trades to the bottom so you don't accidentally interfere with the logic.
It works practically the same as my original QuickTrade, it just uses the command //qt2 instead of //qtr. You can safely load and use both addons at the same time. It still requires you to use the TradeNPC and Itemizer addons.
Some things I do remember:
I added some Abyssea trades with various ???'s in the zones. The trades use your XYZ coordinates along with zone name to determine which ??? you are at. I didn't add many, but you can add more. Find your coordinates at a ??? by standing near it, targeting it, and entering "//qt2 xyz". You can then update the addon with those coordinates and zone name. Crystals and other items that don't have be traded one-type-at-a-time have been updated to be MUCH faster.
There is a huge commented section at the bottom near all the trade details that attempts to explain how the trades are setup. It's mostly accurate, but I didn't go over the details after further testing to clean up the information, so it's probably a bit messy and may not reflect the status of the trades (untested, tested, etc.)
There is an option on line 40: tripleQuestionmarkAlert = false. If you set this to true, it can play a sound when a ??? spawns in Abyssea to get your attention. The sound it plays can be found on line 1004 and you'll have to set it to your own folder and file.
One additional feature that some might not like and might want to disable: I added the ability to detect ???'s spawning in Abyssea and have the character target them automatically using packet injection. You have to be standing right next to them and they have to be the closest targetable thing to you. To disable this function, I think you can just change line 952 from "--return" to "return".
If you have any questions, I most likely won't be able to help, as it's been about a year since I've played, and I don't have an active account to further modify and test the addon.